Image Sharpness & Resolution

Film

The larger the negative, the more the print can be enlarged without losing detail. The smaller the negative, the less it can be enlarged without losing detail.

35 mm	2" x 3"
4" x 5"	8" x 10"

Digital

The size of an image, in pixels, is called its resolution. The higher the number of pixels, the higher the resolution and the more detailed the image will appear. The pixels in high-resolution images cannot be seen. Low-resolution images become "pixellated." The pixels are visible. This compares to the grainy quality of some traditional photographs.

Digital cameras are classed according to resolution. The more pixels the camera has, the higher the print-quality. Top digital cameras have between 5 MPs and 6 MPs, or megapixels. A megapixel is one million pixels.

The size of the digital file on the computer is determined by the resolution. A low-resolution image has a relatively small number of pixels per inch (72 ppi) and a small file size. Low-resolution images are used for the web because they can be loaded more quickly to the web browser. A high-resolution image has a larger number of pixels per inch (300 ppi or higher). High-resolution images are used for printing purposes and CD-ROM production, where file size is less of a concern, and more detail is preferable.

The sharpness of the image on the screen depends on the quality of the monitor. One camera pixel is equal to one computer monitor pixel. Additional pixels will make the image larger on screen but not sharper. Additional pixels only become important when the image is printed on paper. A 1600 x 1200-resolution image typically produces a sharp 6" x 8" print.

72 dpi	640 dpi
2400 dpi	14400 dpi